Improvement in Strain Sensor Stability by Adapting the Metal Contact Layer

Research on stretchable strain sensors is actively conducted due to increasing interest in wearable devices. However, typical studies have focused on improving the elasticity of the electrode. Therefore, methods of directly connecting wire or attaching conductive tape to materials to detect deformation have been used to evaluate the performance of strain sensors. Polyaniline (PANI), a p-type semiconductive polymer, has been widely used for stretchable electrodes. However, conventional procedures have limitations in determining an appropriate metal for ohmic contact with PANI. Materials that are generally used for connection with PANI form an undesirable metal-semiconductor junction and have significant contact resistance. Hence, they degrade sensor performance. This study secured ohmic contact by adapting Au thin film as the metal contact layer (the MCL), with lower contact resistance and a larger work function than PANI. Additionally, we presented a buffer layer using hard polydimethylsiloxane (PDMS) and structured it into a dumbbell shape to protect the metal from deformation. As a result, we enhanced steadiness and repeatability up to 50% strain by comparing the gauge factors and the relative resistance changes. Consequently, adapting structural methods (the MCL and the dumbbell shape) to a device can result in strain sensors with promising stability, as well as high stretchability.

Effects of Minimalist Footwear and Foot Strike Pattern on Plantar Pressure during a Prolonged Running

The use of minimalist shoes (MS) in running involves changes in running mechanics compared to conventional shoes (CS), but there is still little research analysing the effects of this footwear on plantar pressure, which could help to understand some risk injury factors. Moreover, there are no studies examining the effects of a prolonged running and foot strike patterns on baropodometric variables in MS. Therefore, the aim of this study was to analyse the changes produced using MS on plantar pressure during a prolonged running, as well as its interaction with the time and foot strike pattern. Twenty-one experienced minimalist runners (age 38 ± 10 years, MS running experience 2 ± 1 years) ran with MS and CS for 30 min at 80% of their maximal aerobic speed, and mean pressure, peak pressure, contact time, centre of pressure velocity, relative force and contact area were analysed using a pressure platform. Foot strike pattern and time were also considered as factors. The multivariable linear regression mixed models showed that the use of MS induced, at the end of a prolonged running, higher peak pressure (p = 0.008), lower contact time (p = 0.004) and lower contact area (p < 0.001) than using CS. Also, runners with forefoot strike pattern using MS, compared to midfoot and rearfoot patterns, showed higher mean and peak pressure (p < 0.001) and lower contact time and area (p < 0.05). These results should be considered when planning training for runners using MS, as higher peak pressure values when using this type of footwear could be a risk factor for the development of some foot injuries.

Effect of dielectric surface passivation on organic field-effect transistors: spectral analysis of the density of trap-states

The semiconductor/dielectric interface is arguably the most important region in field-effect transistors. This article investigates the performance-enhancing effects of passivation of the dielectric surface by a self-assembled layer (SAM) of silanes on organic field-effect transistors. Apart from conventional figures of merit for the devices, the energetic distribution of the density of the in-gap trap-states (trap-DOS) and the contact resistance are evaluated using numerical methods. The investigation reveals that the surface passivation of the dielectric SiO2 has a dual effect on device operation. Firstly, it establishes quantitatively that the surface passivation leads to a significant reduction in the density of both shallow and deep traps in the organic semiconductor PBTTT-C14. This effect outweighs the impact of the SAM dipoles on the device turn-on. Secondly, the contact resistance gets lowered by a factor of more than 10 due to the improved top-surface morphology of the PBTTT-C14 thin film. The lower contact resistance in devices is corroborated by lower contact potential difference between PBTTT-C14 and gold, measured using scanning kelvin probe microscopy.

The Early Quaternary Marine to Terrestrial Transition of the Southeastern Wairarapa, New Zealand

<p>This study examines the final emergence of the southeastern Wairarapa within a sequence stratigraphic framework. New exposures of the Pleistocene marginalmarine Hautotara Formation, and non-marine Te Muna Formation allow facies to be detailed and sequence architecture to be analysed. Cyclicity observed within the facies successions of the Hautotara and Te Muna formations are placed in a series of four motifs. These motifs record 40 kyr glacioeustatic cyclicity superimposed upon the basinward to landward progression of the environments, showing the region shallowing through time. The positions of the top of the Pukenui Limestone and the base of the Hautotara Formation are revised, and are now at the top of the “Pukenui C” - a widespread marker bed, which also removes a historical nomenclatural gap. The recognition of the significance of the coccolith Gephyrocapsa sinuosa within the underlying Pukenui Limestone allows this contact to be dated at 1.73 Ma. The ~1.6 Ma age limit provided by a number of tephra within the lower sediments of the Te Muna Formation allow the ages of the examined formations to be constrained further. The eight 40 ka cycles identified within the Hautotara Formation suggests deposition between 1.73 and 1.42 Ma. The Hautotara - Te Muna Formation is revealed to be diachronous, with the base of the Te Muna Formation type section shown to be much younger, 1.12 Ma, than the 1.58 Ma age of the lower contact observed elsewhere in the region. A series of palaeogeographic reconstructions at 1.73, 1.58 and 1.57 Ma demonstrate how closely related sedimentation patterns are to structural growth, with marginal-marine Hautotara Formation sedimentation persisting in the centre of the study area well after the initiation of Te Muna Formation terrestrial deposition to the north and south of this site.</p>

The Early Quaternary Marine to Terrestrial Transition of the Southeastern Wairarapa, New Zealand

<p>This study examines the final emergence of the southeastern Wairarapa within a sequence stratigraphic framework. New exposures of the Pleistocene marginalmarine Hautotara Formation, and non-marine Te Muna Formation allow facies to be detailed and sequence architecture to be analysed. Cyclicity observed within the facies successions of the Hautotara and Te Muna formations are placed in a series of four motifs. These motifs record 40 kyr glacioeustatic cyclicity superimposed upon the basinward to landward progression of the environments, showing the region shallowing through time. The positions of the top of the Pukenui Limestone and the base of the Hautotara Formation are revised, and are now at the top of the “Pukenui C” - a widespread marker bed, which also removes a historical nomenclatural gap. The recognition of the significance of the coccolith Gephyrocapsa sinuosa within the underlying Pukenui Limestone allows this contact to be dated at 1.73 Ma. The ~1.6 Ma age limit provided by a number of tephra within the lower sediments of the Te Muna Formation allow the ages of the examined formations to be constrained further. The eight 40 ka cycles identified within the Hautotara Formation suggests deposition between 1.73 and 1.42 Ma. The Hautotara - Te Muna Formation is revealed to be diachronous, with the base of the Te Muna Formation type section shown to be much younger, 1.12 Ma, than the 1.58 Ma age of the lower contact observed elsewhere in the region. A series of palaeogeographic reconstructions at 1.73, 1.58 and 1.57 Ma demonstrate how closely related sedimentation patterns are to structural growth, with marginal-marine Hautotara Formation sedimentation persisting in the centre of the study area well after the initiation of Te Muna Formation terrestrial deposition to the north and south of this site.</p>

Effect of Overlapping Eco-Friendly Cellulose Nanofibrils and Nanoclay Layers on Mechanical and Barrier Properties of Spray-Coated Papers

This work proposes to evaluate the effect of spray-coating in papers using eco-friendly cellulose nanofibrils (CNFs) and nanoclay (NC) on mechanical and barrier properties for application as reinforced bags. Sack kraft papers of 60 g m-² (C60) were coated with CNFs + CNFs/NC in 4 layers (L5), 40 g m-² of CNFs + CNFs/NC in 3 layers (L4), 30 g m-² with CNFs/NC in 2 layers (L3) and 10 g m-² of CNFs in 1 layer (L2), and compared to uncoated sack kraft papers with basis weight of 60 g m-² (C60), 80 g m-² (C80) and 120 g m-² (C120). The coated papers L2; L3; L4 and L5 obtained a decrease in water vapor transmission rate (WVTR) of 3.5%; 17%; 14% and 14%, respectively, when compared to C60. Comparing L2 and L3, CNF layer induced lower contact angles on the coated paper than CNF/NC layer. When compared coated papers with C120, it was observed an increase of around 66% in tensile strength for L2, around 44% for L3, and decrease of ~ 18% for L5 coated papers. L4 achieved the same tensile strength (when divided by basis weight) than C120. L2 and L3 coated papers led to the highest values of Young’s modulus, with increase of 56% and 38%, respectively, when compared to C60. Spray-coating in the present conditions improved the mechanical and barrier properties of the coated papers, being a possible alternative to produce papers with lower basis weight and using renewable raw materials.

Stratigraphic distribution of the Codell Sandstone in the Denver Basin using wireline logs and core

Core data from five key wells spanning the Denver Basin were tied to wireline log data and used to interpret the distribution of the Middle Turonian Codell Sandstone Member of the Carlile Formation across the Denver Basin. The character of the Codell’s upper contact is sharp with a localized top-down truncation across the basin, which is consistent with an associated unconformity surface. In contrast, the Codell’s lower contact varies from being gradational in most of the southern Denver Basin to being unconformable in the northern basin. Log correlations reveal that the Codell is absent within an elongate northeast-trending swath up to 125 miles wide in northeastern Colorado. This elongate gap is herein referred to as the ‘No Codell Zone’ abbreviated as NoCoZo. Hypotheses to explain the absence of the Codell Sandstone in the NoCoZo include a lateral facies change from sandstone to shale, non-deposition of Codell-equivalent sediments across this area, post-depositional erosion, or a combination of these processes. Correlation of wireline logs across the northern and southern limits of the NoCoZo, combined with outcrop and core observations, suggest top-down erosion of the Codell increasing into the NoCoZo. However, the overlying Fort Hays Limestone is laterally continuous and has a relatively consistent thickness across the NoCoZo, suggesting two tenable hypotheses: 1) The NoCoZo represents an area of post-Codell erosion due to short-lived growth of a broad, low relief uplift that was no longer active during Fort Hays deposition; or 2) A stepped sea level fall and forced regression resulting in non-deposition of the Codell over this broad swath. North of the NoCoZo, the Codell thickens northward to more than 40 ft into adjacent parts of Wyoming and Nebraska. In this northern area, the Codell has two main lithofacies in three laterally correlative zones, in ascending order: a lower bioturbated siltstone to very fine-grained sandstone ranging from 2 to 20 feet thick, a middle 2 to 10-foot thick laminated to bedded siltstone to fine-grained sandstone, and an upper 5 to 20-foot thick bioturbated siltstone to very fine-grained sandstone. Southeast of the NoCoZo the Codell thickens to as much as 80 feet in an east-trending belt from Pueblo, Colorado, into west central Kansas. The southern Codell can be divided into two coarsening upward parasequences, from a basal muddy coarse siltstones to very fine-grained sandstones. The siltstones and sandstones in the southern Codell are mostly bioturbated with locally developed bedded facies at the top.

The Effect of Using Micro-Clustered Water as a Polymer Medium

The aim of the study was to investigate the changes within the physicochemical properties of gelatin, carrageenan, and sodium alginate hydrosols prepared on the basis of micro-clustered (MC) water. The rheological parameters, contact angle and antioxidant activity of hydrosols were investigated. Moreover, the pH, oxidation–reduction potential (ORP) and electrical conductivity (EC) were measured. The hydrosols with MC water were characterized by a lower pH, decreased viscosity, a lower contact angle, and only slightly lower antioxidant activity than control samples. The results showed that hydrosol’s properties are significantly changed by MC water, which can lead to enhancement of its applicability but requires further investigation.

Water purification performance enhancement of PVC ultrafiltration membrane modified with tourmaline particles

In this study, a novel PVC/tourmaline ultrafiltration membrane was fabricated by phase inversion method in order to improve anti-fouling performance and water quality. FESEM was used to examine the changes in the morphology of pure PVC and PVC/tourmaline hybrid membranes. The introduction of tourmaline resulted in the increase of porosity and mean pore size. EDX images indicated that tourmaline particles were homogeneously dispersed in the membranes when the amount were less than 1.0 wt%. The hybrid membranes exhibited lower contact angle (78.7°) and higher water flux (121.3 L/m2 h) than the pure PVC membrane. The anti-fouling performance of the membranes were studied by filtration of BSA solution. The results demonstrated that the hybrid membrane with 1.0 wt% tourmaline particles exhibited the best anti-fouling performance and the highest BSA rejection. In addition, the pH and conductivity of the filtered water were measured by pH meter and electrical conductivity meter. And the results showed that the quality of the filtered water was improved after treating through the hybrid membranes.